In mobile networks when using Multiple Carrier Power Amplifier (MCPA) Radio Base Stations (RBSs) there will be a risk that the available power will not be enough for all information to be sent during a specific time period on a specific frequency.
For shorter periods of time (peaks) there is a certain margin for power overload. But if that margin is exceeded the output signal will be distorted and causing inter modulation (IM) products affecting both transmission on that particular frequency itself and adjacent frequencies.
There are several solutions for how to solve this, with small or large impact to one or several of the users of the MCPA. Furthermore, there are several ways to minimize the risk for power congestion, by power reduction, prediction and spreading of the users to different time slots and frequencies/MCPAs.
In FIG. 1 an exemplary scenario where the peak power allocation is exceeded in a time slot is depicted. Thus, for an MCPA if the combined power required by the multiple carriers exceeds the available power output from the MCPA some action needs to be taken or the signal will be distorted.
For Global System for Mobile Communication (GSM) based MCPA RBSs a major problem is that the power requirements are typically largely determined by the Base Station Controller (BSC), for each MCPA carrier separately. And it is first when the different MCPA carriers are added in the Base Transceiver Station (BTS) that the negative peak effects get visible, as well as the positive effects of discontinuous transmission. At that time the BSC cannot change the power order. As a result there may be an over demand of power for a particular Time Slot (TS).
One of the most difficult tasks is to minimize the power need during the periods when the Slow Associated Control Channel (SACCH) information is to be sent out. The reason is that all ongoing Circuit Switched (CS) connections must transmit at the same time in accordance with Third Generation Partnership Project (3GPP) specification No, 45.002. Furthermore, when using Discontinuous Transmission there are specific periods when all ongoing connections must transmit Silence Detection (SID) frames in accordance with according to 3GPP specification No. 45.008 during periods of silence. This applies to all speech calls using a specific rate and mode namely FR/speech, HR/speech, FR/data or HR/data.
Hence, there exist a need for a method and a system that is able to improve power allocation in transmission of data.